1. Technical Field
The present invention relates generally to power conversion, and more particularly to an isolated power conversion apparatus and a method of converting power.
2. Description of Related Art
The most significant difference between isolated power transfer systems and typical power transfer systems is that the former transmit energy by an isolated transformer to transmit energy from a primary side to a secondary side through electromagnetic coupling rather than by wires. However, the power conversion efficiency of the isolated power transfer systems is lower than typical ones due to the limitation of coupling effect. Therefore, the conventional isolated power transfer systems are usually applied with resonant impedance matching to enhance the power conversion efficiency. But circuits with impedance matching tend to be affected by the coupling coefficient of corresponding transformers, and therefore fail to reach expected performance. Besides, only if an output voltage of a power transfer system is higher than a voltage of a connected loading to overcome an electric potential barrier of the output terminal, the loading can then be provided with energy; hence a transformer with larger turn ratio is needed in isolated power transferring circuits to increase voltage to required level. Unfortunately, the copper loss of transformers increases with higher turn ratio, which lowers the power conversion efficiency again.